diff --git a/src/de/inetsoftware/jwebassembly/module/JavaMethodWasmCodeBuilder.java b/src/de/inetsoftware/jwebassembly/module/JavaMethodWasmCodeBuilder.java
index d2d3980..33a93a2 100644
--- a/src/de/inetsoftware/jwebassembly/module/JavaMethodWasmCodeBuilder.java
+++ b/src/de/inetsoftware/jwebassembly/module/JavaMethodWasmCodeBuilder.java
@@ -80,7 +80,7 @@ class JavaMethodWasmCodeBuilder extends WasmCodeBuilder {
                 int codePos = byteCode.getCodePosition();
                 endWithReturn = false;
                 int op = byteCode.readUnsignedByte();
-                switch( op ) {
+                OP: switch( op ) {
                     case 0: // nop
                         break;
                     //TODO case 1: // aconst_null
@@ -224,11 +224,24 @@ class JavaMethodWasmCodeBuilder extends WasmCodeBuilder {
                         addBlockInstruction( WasmBlockOperator.DROP, null, codePos );
                         break;
                     case 89: // dup: duplicate the value on top of the stack
-                        addCallInstruction( new SyntheticMember( "de/inetsoftware/jwebassembly/module/NativeHelperCode", "dup_i32", "(I)II" ), codePos );
-                        break;
+                    case 92: // dup2
+                        switch( findPreviousPushInstruction().getPushValueType() ) {
+                            case i32:
+                                addCallInstruction( new SyntheticMember( "de/inetsoftware/jwebassembly/module/NativeHelperCode", "dup_i32", "(I)II" ), codePos );
+                                break OP;
+                            case f32:
+                                addCallInstruction( new SyntheticMember( "de/inetsoftware/jwebassembly/module/NativeHelperCode", "dup_f32", "(F)FF" ), codePos );
+                                break OP;
+                            case i64:
+                                addCallInstruction( new SyntheticMember( "de/inetsoftware/jwebassembly/module/NativeHelperCode", "dup_i64", "(J)JJ" ), codePos );
+                                break OP;
+                            case f64:
+                                addCallInstruction( new SyntheticMember( "de/inetsoftware/jwebassembly/module/NativeHelperCode", "dup_f64", "(D)DD" ), codePos );
+                                break OP;
+                        }
+                        //$FALL-THROUGH$
                     case 90: // dup_x1
                     case 91: // dup_x2
-                    case 92: // dup2
                     case 93: // dup2_x1
                     case 94: // dup2_x2
                     case 95: // swap
@@ -557,7 +570,7 @@ class JavaMethodWasmCodeBuilder extends WasmCodeBuilder {
             byteCode.skip( 4 - padding );
         }
         startPosition--;
-        int switchValuestartPosition = findPreviousPushCodePosition();
+        int switchValuestartPosition = findPreviousPushInstruction().getCodePosition();
 
         int defaultPosition = startPosition + byteCode.readInt();
         int[] keys;
@@ -620,12 +633,13 @@ class JavaMethodWasmCodeBuilder extends WasmCodeBuilder {
     }
 
     /**
-     * We need one value from the stack inside of a block. We need to find the code position on which the block can
+     * We need one value from the stack inside of a block. We need to find the WasmInstruction on which the block can
      * start. If this a function call or numeric expression this can be complex to find the right point.
      * 
-     * @return the code position
+     * @return the WasmInstruction that push the last instruction
      */
-    private int findPreviousPushCodePosition() {
+    @Nonnull
+    private WasmInstruction findPreviousPushInstruction() {
         int valueCount = 0;
         List<WasmInstruction> instructions = getInstructions();
         for( int i = instructions.size() - 1; i >= 0; i-- ) {
@@ -636,10 +650,10 @@ class JavaMethodWasmCodeBuilder extends WasmCodeBuilder {
             }
             valueCount -= instr.getPopCount();
             if( valueCount == 1 ) {
-                return instr.getCodePosition();
+                return instr;
             }
         }
-        throw new WasmException( "Switch start position not found", -1 ); // should never occur
+        throw new WasmException( "Start position not found", -1 ); // should never occur
     }
 
     /**
diff --git a/src/de/inetsoftware/jwebassembly/module/NativeHelperCode.java b/src/de/inetsoftware/jwebassembly/module/NativeHelperCode.java
index c583ad9..09e488b 100644
--- a/src/de/inetsoftware/jwebassembly/module/NativeHelperCode.java
+++ b/src/de/inetsoftware/jwebassembly/module/NativeHelperCode.java
@@ -22,4 +22,12 @@ public class NativeHelperCode {
     @WasmTextCode( signature = "(I)II", value = "get_local 0 get_local 0 return" )
     native static void dup_i32();
 
- }
+    @WasmTextCode( signature = "(F)FF", value = "get_local 0 get_local 0 return" )
+    native static void dup_f32();
+
+    @WasmTextCode( signature = "(J)JJ", value = "get_local 0 get_local 0 return" )
+    native static void dup_i64();
+
+    @WasmTextCode( signature = "(D)DD", value = "get_local 0 get_local 0 return" )
+    native static void dup_f64();
+}
diff --git a/test/de/inetsoftware/jwebassembly/runtime/Stacks.java b/test/de/inetsoftware/jwebassembly/runtime/Stacks.java
index 9827246..a1ab68b 100644
--- a/test/de/inetsoftware/jwebassembly/runtime/Stacks.java
+++ b/test/de/inetsoftware/jwebassembly/runtime/Stacks.java
@@ -45,7 +45,10 @@ public class Stacks extends AbstractBaseTest {
             if( script == ScriptEngine.SpiderMonkey ) { //TODO SpiderMonkey does not support multiple return values
                 continue;
             }
-            addParam( list, script, "simple" );
+            addParam( list, script, "dupInt" );
+            addParam( list, script, "dupFloat" );
+            addParam( list, script, "dupDouble" );
+            addParam( list, script, "dupLong" );
         }
         return list;
     }
@@ -53,11 +56,35 @@ public class Stacks extends AbstractBaseTest {
     static class TestClass {
 
         @Export
-        static int simple() {
+        static int dupInt() {
             int a = 1;
             int b = 2;
             a = b = 3;
             return b;
         }
+
+        @Export
+        static float dupFloat() {
+            float a = 1;
+            float b = 2;
+            a = b = 3.25F;
+            return b;
+        }
+
+        @Export
+        static double dupDouble() {
+            double a = 1;
+            double b = 2;
+            a = b = 3.25;
+            return b;
+        }
+
+        @Export
+        static int dupLong() {
+            long a = 1;
+            long b = 2;
+            a = b = 3;
+            return (int)b;
+        }
     }
 }